Screw piles have long been commonly used in connection with foundation underpinning, pipeline tie-downs and in other applications.
In one known embodiment, the screw pile comprises:                an open ended tubular shaft having one or more helixes externally mounted thereon adjacent its pointed lower end;        the shaft usually comprises a bottom anchor section carrying the helixes and one or more extension sections;        the shaft has means, such as pin holes, at its upper end, for insertion of locking pins to connect the shaft with a drive head assembly which functions to rotate the pile into the ground.        
A screw pile will be characterized by load-carrying and lateral deflection capacities, once implanted in the ground.
The load-carrying capacity of a screw pile can be increased by increasing its length and/or diameter or increasing the number of helixes. However these changes will require that greater torque be applied by the drive head assembly in order to rotate the pile into place at the desired landed depth. There are finite limits on the amount of torque that can be applied to the pile and on the capability of the drive head assembly to deliver it.
In addition, the nature of the ground into which the pile is implanted will also affect the load-carrying capacity of the pile.
It is known to inject grout, such as cement slurry, at low pressure, down through the bore of the hollow shaft and out, through ports in its side wall, into the sub-surface formation or stratum in which the pile has been landed, to thereby increase the stiffness of the formation and enhance the load capacities of the pile.
The present invention is concerned in one aspect with providing a modified screw pile and in another aspect with providing a method of installation, which have the objective of increasing the load capacities of an implanted pile.